I am the original author of this article which was posted here.
Two things

1. I see there is some debate on my use of the terminology and the meaning between "hard fork" vs "soft fork". I always thought a hard-fork was when something was not backwards compatible. Maybe I got the terminology wrong, but either way, I am correct that BIP110 is a planned fork that will be incompatible with bitcoin due to it being an incorrect chain, or incorrect PoW if Luke Dash jr gets his way.
2. There are two ways I identified in which BIP110 transactions will be incompatible with Bitcoin. One is due to coins on BIP110 having a shared history with BIP110-mined coins which would be unrecognized on Bitcoin. Another is when transactions end up being mined on BIP110 instead of Bitcoin. Even if a transaction would otherwise be valid on both chains, these are two scenarios where it that cross-chain compatibility would break.
3. Thanks to those who pointed out the maximum difficulty adjustment, I learned something new there. Either way, it will still take a very long time for BIP110 to get confirmations and for it to reach difficulty adjustment unless it changes the PoW which would permanently make it incompatible with Bitcoin by referencing incorrect difficulty in each block.